Dynamic behavior of magnetically responsive shear-stiffening gel under high strain rate

The dynamic mechanical behavior of the magnetically responsive shear-stiffening gel (MSTG) was investigated by using a modified Split Hopkinson Pressure Bar (SHPB) system. It was found that the elastic modulus of the MSTG increased with increasing strain rate and magnetic field. The elastic modulus of the MSTG with 45 wt% carbonyl iron (CI) particles reached to 126.6 MPa at the strain rate of 7236 s−1, while it was merely 160 Pa without excitation. Under a 300 mT magnetic field, the elastic modulus also increased from 116.5 MPa (no magnetic field) to 255.5 MPa at the strain rate of 2900 s−1. The shear stiffening performance of the MSTG was stable and its maximum yield strain was 17.2%, which was very important for its practical application. The magnetically strengthened mechanisms of the high strain-rate-dependent mechanical properties were proposed. It was found that the enhanced shear-stiffening behavior was attributed to the phase transitions from viscous-liquid state to elastomeric state to glassy state under impact.